Mergers and Acquisitions (Details2) $ in Thousands	Aug. 21, 2015 USD ($) location	Sep. 30, 2015 USD ($)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Goodwill		$ 338,300
Bank of America
Mergers and Acquisitions
Business Acquisition Deposit Premium	5.50%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and cash equivalents	$ 428,567
Loans	3,148
Premises and equipment	4,129
Intangible assets	6,800
Other assets (acquired)	66
Total assets	442,710
Deposits	438,289
Other liabilities (acquired)	56
Total liabilities	438,345
Net identifiable assets acquired over (under) liabilities assumed	4,365
Goodwill	20,654
Net assets acquired over liabilities assumed	25,019
Business combination deposit premium paid	25,019
Fair value of total consideration transferred	25,019
Bank of America | Interest-bearing Deposits [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Deposits	340,849
Bank of America | Non interest-bearing deposits [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Deposits	97,440
Bank of America | As previously recorded by acquiree
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and cash equivalents	428,567
Loans	3,445
Premises and equipment	6,267
Other assets (acquired)	66
Total assets	438,345
Deposits	438,289
Other liabilities (acquired)	56
Total liabilities	438,345
Bank of America | As previously recorded by acquiree | Interest-bearing Deposits [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Deposits	340,849
Bank of America | As previously recorded by acquiree | Non interest-bearing deposits [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Deposits	97,440
Bank of America | Fair Value Adjustments
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Loans	(297)
Premises and equipment	(2,138)
Intangible assets	6,800
Total assets	4,365
Net identifiable assets acquired over (under) liabilities assumed	4,365
Goodwill	20,654
Net assets acquired over liabilities assumed	$ 25,019
Bank of America | South Carolina [Member]
Mergers and Acquisitions
Number of branches | location	12
Bank of America | Georgia [Member]
Mergers and Acquisitions
Number of branches | location	1